1. Field of the Invention
This invention relates to the treatment of formations surrounding oil wells, gas wells and similar boreholes. In one aspect, it relates to the control of fines migration in a formation using resin applications.
2. Description of the Prior Art
Declines in the productivity of oil and gas wells are frequently caused by the migration of fines toward the wellbore of a subterranean formation. Fines, which normally consist of minutely sized clay and sand particles, can plug and damage a formation and may result in up to a 20-fold reduction in permeability. Conventional sand control techniques such as gravel packing and sand consolidation are sometimes ineffective because fines are much smaller than sand grains and normally cannot be filtered or screened out by gravel beds or consolidated sand. In addition, gravel packing and sand consolidation are normally confined to areas surrounding the immediate vicinity of the wellbore. Fines movement, however, can cause damage at points which are deep in the producing zone of the formation as well as points which are near the wellbore region.
Two types of fines control are in current use -- acidizing and clay stabilization. Acidizing removes fines by dissolving them with acidic or caustic solutions. Acidizing, however, will frequently dissolve coarse particles, such as gravel and sand, as well as fines and excess acidization may regenerate fines if the coarser particles are sufficiently eroded. Clay stabilization is directed at the well damage caused by the migration of clay fines. Because clay fines have a tendency to swell in the presence of aqueous well fluids, they create disproportionately greater damage than other fines. Therefore, clay stabilization techniques are directed at either inhibiting clay swelling or floculating the clay particles. Such preventive treatments are used only after the particles begin to move and do not prevent fines movement in the first instance. Clay stabilization also fails to control the migration of nonclay fines. Consequently, a treatment technique is needed which controls the fines before they even begin to migrate in the formation.